It is known to produce a concrete tunnel lining with the aid of a tunnel form comprising a plurality of tunnel form segments around which a circular space is provided, which is closed by a form front at its front end next to the tunnel excavator and at its opposing rear end by the hardened or progressively hardening concrete of the tunnel lining.
Into the tunnel lining circular space, concrete is pumped as the form front advances.
The tunnel form segments are repositioned following the progressing tunnel excavator after hardening of the concrete. Upon removal of a segment, the strength of the freshly formed concrete should be such that the concrete can already stand alone and withstand the weight of the surrounding structure without the removed form.
The strength of the freshly formed concrete add its setting rate is however dependent on the composition of the concrete and can be adjusted with suitable additives.
In any case, after hardening of the concrete to an adequate strength, the tunnel form can be repositioned. This hardening usually requires many hours. Generally the hardening spreads from the rear end of the tunnel lining circular space into the concrete which is pumped in at a later time.
The form elements or rings constituted of the tunnel form segments are repositioned starting with the rearmost section to follow the progressing tunnel excavator.
In practice, a tunnel form of 20 to 50 m in length must always remain. Because of this length, necessary to ensure that a self-supporting lining of concrete is formed, a sliding form cannot be used. Attempts to use sliding forms in constructing a concrete tunnel lining have failed for the most part.
A heating treatment for promoting the hardening of concrete to a sufficient strength is already known. These known treatments, however, have not been successful with tunnel lining. In one known process for making a tunnel lining according to German Open Patent Application DE-OS 27 03 536, only the region near the form is heated. The heat is supplied to the concrete by comparatively slow conduction through the metal shell. Also the hardening occurs from the form side to the interior of the concrete which is disadvantageous.